CN110267318B

CN110267318B - Base station, user equipment and method thereof in heterogeneous network

Info

Publication number: CN110267318B
Application number: CN201910639580.1A
Authority: CN
Inventors: G-J.范利舒特; S.N.S.贾马达格尼; M.A.英戈尔
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2012-03-06
Filing date: 2013-03-06
Publication date: 2021-09-07
Anticipated expiration: 2033-03-06
Also published as: EP2823671B1; EP2823671A4; US20150139053A1; JP2015509688A; US9794872B2; EP2823671A1; CN104186011A; WO2013133630A1; CN110267318A; JP2017118586A

Abstract

Disclosed is a base station in a heterogeneous network, comprising: at least one processor; and a transceiver configured to: transmitting a message for cell reselection comprising information indicating a reduced measurement, and receiving a measurement report comprising a measurement result measured based on the information from a user equipment, UE, wherein a time factor related to the reduced measurement is different from a time factor related to a normal measurement, and wherein the reduced measurement and the normal measurement are performed for at least one same frequency.

Description

Base station, user equipment and method thereof in heterogeneous network

The present application is a divisional application of the following applications: application No.: 201380012892.0, filing date: 3, month 06 in 2013, the invention name is: "method and system for minimizing power consumption of user equipment during cell detection".

Technical Field

The present invention relates to a heterogeneous network, and more particularly, to a base station, a user equipment, and methods thereof in a heterogeneous network.

Background

In wireless communication systems, ubiquitous coverage is a fundamental requirement of cellular network operators. Wireless communication systems mainly include homogeneous and heterogeneous deployments of cells. In a homogeneous deployment, there will be a uniform cell size or coverage area, whereas in the case of a heterogeneous network, the cell size varies according to the deployment of different types of cells. The heterogeneous deployment topology includes hybrid cells served by high power macro evolved node bs (enbs) and low power pico or femto enbs or relay nodes within a geographic area.

In an LTE system, an evolved universal terrestrial radio access network (E-UTRAN) includes a plurality of evolved node bs (enbs) and communicates with a plurality of mobile stations, also referred to as User Equipment (UE).

In the LTE system, a User Equipment (UE) may perform measurement for measuring radio link quality, such as quality of a frequency channel (frequency channel) or strength of a radio signal, in order to facilitate handover due to mobility of the UE. Measurements may be divided into two types according to the current operating frequency of the UE: intra-frequency measurements and inter-frequency/inter-RAT measurements.

Intra-frequency measurements are mainly performed for mobility within the same frequency channel (between cells operating on the same carrier frequency); while inter-frequency/Radio Access Technology (RAT) measurements are mainly performed for mobility between different frequency channels, i.e. between cells operating on different carrier frequencies.

Further, inter-frequency/inter-RAT measurements are performed during a measurement gap (gap) configured by the network. Furthermore, during the measurement gap, both uplink and downlink transmissions are suspended (e.g., no Physical Uplink Control Channel (PUCCH), Physical Uplink Shared Channel (PUSCH), Physical Downlink Control Channel (PDCCH), and Physical Downlink Shared Channel (PDSCH) transmissions), so that inter-frequency/inter-RAT measurements may be performed within the measurement gap.

In LTE, inter-frequency neighbor cell search (measurement) is performed within a gap length of 6 milliseconds (ms) for both Time Domain Duplex (TDD) and Frequency Domain Duplex (FDD) systems. However, switching between the frequency of the serving cell and the frequency on which a new cell needs to be detected takes some time. The remaining time of the gap (slightly less than 6 milliseconds) may be utilized for neighbor cell search on one or more configured frequencies other than the serving frequency. Thus, the actual time for neighbor cell search will be less than 6ms within one gap duration.

Inter-frequency heterogeneous network deployments may be asynchronous, such that radio frame timing of one cell is not aligned with radio frame timing of other neighboring cell(s). The measurement gaps are standardized in the LTE specification (TS36.331) and have a periodicity of 40ms or 80 ms.

To maximize the offloading opportunities, generally, the operator configures a continuous scan of the picocell frequencies to look for any possible offloading opportunities. This greatly increases the amount of time the UE spends in scan mode.

Furthermore, in a heterogeneous network scenario where smaller cells are deployed for the purpose of offloading users from the macro cell, constantly using inter-frequency measurements with the currently standardized measurement gap pattern (gap pattern) and measurement rules will quickly drain the UE battery. Battery consumption is proportional to the picocell deployment density within the macrocell.

The currently defined gap patterns were originally designed for mobility purposes within the deployment scenario of macro-cells only, which is quite sparse compared to heterogeneous deployments. The measurement gaps are designed and optimized to allow fast inter-frequency/inter-RAT cell search and enable fast mobility when needed in a macro-cell only deployment scenario. Furthermore, in a macro-cell only network, inter-frequency measurements are made when the network needs them in order to offload traffic to different frequency layers or for mobility reasons.

Disclosure of Invention

Technical problem

In view of the above discussion, it is desirable to have a mechanism to provide a method and system for minimizing battery consumption of a UE during inter-frequency cell discovery in a heterogeneous network deployment, while not disrupting any possible offloading opportunities.

Technical scheme

A primary object of embodiments herein is to provide a method and system for minimizing battery consumption of user equipment during inter-frequency cell detection in dense wireless cell deployment scenarios.

Another object of the present invention is to provide a method and system for detecting an inter-frequency cell by a user equipment in an inactive time (inactive time) of a discontinuous reception period.

The present invention therefore provides a method for minimizing battery power consumption by a User Equipment (UE) during inter-frequency cell detection in a Radio Resource Control (RRC) connected mode in a heterogeneous network, wherein the method comprises sending, by the network, a background scanning configuration to the UE based on a cell density decision. The method includes receiving, by a UE, a background scanning configuration for at least one configured frequency to initiate a cell search on a configured frequency during an inactive time of a Discontinuous Reception (DRX) cycle, wherein the configured frequency is a frequency other than a serving frequency. The method then detects the at least one cell on the configured frequency using the background scanning configuration. Further, the method indicates, by the UE, to the network a Physical Cell Identity (PCI) of the at least one detected cell on the configured frequency. Further, the method includes activating a normal measurement gap when the UE is previously configured by the network.

The present invention therefore provides a network for minimizing battery power consumption by a User Equipment (UE) during inter-frequency cell detection in a Radio Resource Control (RRC) connected mode in a heterogeneous network, wherein the network is configured to send a background scanning configuration to the UE based on a cell density decision. The network is configured to provide a background scanning configuration for at least one configured frequency to the UE for the UE to initiate a cell search on a configured frequency during an inactive time of a Discontinuous Reception (DRX) cycle, wherein the configured frequency is a frequency other than a serving frequency. Further, the network is configured to receive a Physical Cell Identity (PCI) of at least one detected cell from the UE on a configured frequency configured for background scanning. The network is configured to: if not previously provided in the measurement configuration, the UE is reconfigured with normal measurement gaps. Further, the network is configured to: upon receiving a PCI of at least one cell detected by the UE on a configured frequency configured for background scanning, transmitting a measurement report event condition for the at least one configured frequency. Finally, the network is configured to perform handover of the UE to a cell detected on the configured frequency based on satisfaction of the measurement report event condition.

Accordingly, the present invention provides a User Equipment (UE) for inter-frequency cell detection in a Radio Resource Control (RRC) connected mode in a heterogeneous network, wherein the UE comprises an integrated circuit. Further, the integrated circuit comprises at least one processor, at least one memory. The memory also includes computer program code within the circuitry. The at least one memory and the computer program code with the at least one processor cause the UE to receive a background scanning configuration for at least one configured frequency from a network to initiate a cell search on the configured frequency during an inactive time of a Discontinuous Reception (DRX) cycle, wherein the configured frequency is a frequency other than a serving frequency. Further, the UE is configured to detect the at least one cell on the configured frequency using a background scanning configuration. The UE is then configured to indicate to the network a Physical Cell Identity (PCI) of the at least one detected cell on the configured frequency. Further, the UE is configured to activate a normal measurement gap if the network has preconfigured the normal measurement gap and receive the normal measurement gap if not preconfigured. Finally, the UE is configured to receive a measurement report event condition for the configured frequency from the network.

According to an aspect of the present invention, there is provided a base station in a heterogeneous network, including: at least one processor; and a transceiver configured to: transmitting a message for cell reselection comprising information indicating a reduced measurement, and receiving a measurement report comprising a measurement result measured based on the information from a user equipment, UE, wherein a time factor related to the reduced measurement is different from a time factor related to a normal measurement, and wherein the reduced measurement and the normal measurement are performed for at least one same frequency.

According to an aspect of the present invention, there is provided a user equipment UE in a heterogeneous network, including: at least one processor; and a transceiver configured to: receiving a message for cell reselection from a base station, the message including information indicating a reduced measurement, and transmitting a measurement report including a measurement result based on the information measurement to the base station, wherein a time factor related to the reduced measurement is different from a time factor related to a normal measurement, and wherein the reduced measurement and the normal measurement are performed for at least one same frequency.

According to an aspect of the present invention, there is provided a method of a base station in a heterogeneous network, including: transmitting a message for cell reselection, the message including information indicating reduced measurements; and receiving a measurement report including a measurement result measured based on the information from a User Equipment (UE), wherein a time factor related to the reduced measurement is different from a time factor related to the normal measurement, and wherein the reduced measurement and the normal measurement are performed for at least one same frequency.

According to an aspect of the present invention, there is provided a method of a User Equipment (UE) in a heterogeneous network, comprising: receiving a message for cell reselection from a base station, the message including information indicating reduced measurements; and transmitting a measurement report including a measurement result based on the information measurement to the base station, wherein a time factor related to the reduced measurement is different from a time factor related to the normal measurement, and wherein the reduced measurement and the normal measurement are performed for at least one same frequency.

These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It will be understood, however, that the following description, while indicating preferred embodiments and numerous details thereof, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

Drawings

The present invention is illustrated in the accompanying drawings in which like reference characters refer to the corresponding parts throughout the various views. The embodiments herein will be better understood from the following description with reference to the accompanying drawings, in which:

fig. 1 shows a block diagram of a user equipment having a plurality of modules in accordance with embodiments disclosed herein;

fig. 2 illustrates an exemplary scenario of inter-frequency measurements by a user equipment in the prior art;

fig. 3 illustrates inter-frequency picocell detection by a user equipment using a background scanning configuration, according to embodiments disclosed herein;

fig. 4 shows a flow chart illustrating a process involved in a user equipment detecting an inter-frequency cell according to embodiments disclosed herein; and

fig. 5 illustrates a computing environment implementing methods and systems for minimizing battery power consumption in a user equipment during inter-frequency cell detection in accordance with embodiments disclosed herein.

Detailed Description

The details of the embodiments herein and the various features and advantages thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

Embodiments herein implement a method and system for minimizing battery power consumption by a User Equipment (UE) during inter-frequency pico cell discovery in a Radio Resource Control (RRC) connected mode in a heterogeneous network deployment. The UE receives a background scanning configuration for a specified frequency from the network and performs background scanning on the specified frequency for detecting an inter-frequency cell (inter-frequency cell).

Throughout this description, the terms network and heterogeneous network consisting of macro cells and pico cells are used interchangeably.

In an embodiment, the background scan configuration includes a background scan indicator, a periodicity of the scan, a density of cells on a frequency, and a list of frequencies for background scanning.

Typically, the network configures the UE to perform inter-frequency measurements using a measurement configuration. The measurement configuration includes a measurement purpose, a reporting configuration, a measurement identity (identity), and a measurement gap configuration for each frequency. With the background scanning configuration, the network indicates for which configured frequency the UE is expected to perform cell search using the background scanning method according to the measurement configuration (measurement purpose). Upon receiving the background scanning indication, the UE detects an inter-frequency cell on a frequency indicated by the network in the background scanning configuration. When a cell is detected during the background scanning mode, the UE indicates to the network a physical cell identity of the detected cell. The network then configures the UE with normal measurement gaps if no measurement gaps are provided in the measurement configuration. Otherwise the UE stops the background scanning and applies the measurement gaps provided earlier in the measurement configuration to perform normal measurements. The configuration for normal measurements of the UE, which has been configured for background scanning, may be triggered by either detecting a smaller cell or reporting a smaller cell to the network.

In an embodiment, the configuration of normal measurements may be triggered by the network based on a determination of the density of picocells in a geographic area.

Further, the UE performs Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) measurements of the detected cell on other frequencies by applying normal measurement gaps. The UE then reports these measurements to the network when the measurement reporting event condition is met. Finally, when the measurements of RSRP and RSRQ are satisfied, the network switches the UE to the detected cell.

Referring now to the drawings, and more particularly to fig. 1 through 5 (wherein like reference characters designate corresponding features throughout the several views), there are shown preferred embodiments.

Fig. 1 illustrates a block diagram of a user device having multiple modules in accordance with embodiments disclosed herein. As depicted in the figure, the user device 100 includes a communication interface module 101, a power module 102, a display module 103, and a processor module 104. The communications interface module 101 facilitates the connection of the UE to the access network. The power module 102 maintains battery information and the state of battery power in the user device 100. The battery information includes a charge amount that the device has and a time period during which the user device 100 can still operate, and the like. The display module 103 of the user device 100 may comprise a user interface, which may be a keyboard, or any other means by which a user may input some data into the user device 100. The processor module 104 provides processing, I/O scanning, logic, control, and communication functions in the user device 100. The processor module is configured in this way: the UE100 detects the inter-frequency pico cell in the heterogeneous network by minimizing battery power consumption of the UE 100. The background scanning configuration provided by the network is run by the UE in the processor module 104.

Fig. 2 illustrates an exemplary scenario of inter-frequency measurement by a user equipment in the prior art. As depicted in the figure, UE100 is being served by cell 201 on frequency f 1. When the UE moves away from the coverage of cell 201, UE100 detects cell 202 on frequency f2 and measures the signal strength of cell 202 to initiate the handover procedure. Cells 201, 202 and 203 are operating on different frequencies, i.e. f1, f2 and f3, respectively. Normally, the network configures the UE with a measurement configuration for performing inter-frequency measurements to facilitate handover.

The cell search (initial cell search) is performed when the UE100 is turned on and also during idle and connected (active) modes (neighbor cell search). Neighbor cell searches (measurements), also referred to as target cell searches (measurements), are performed periodically to find the candidate cell with the best signal strength for handover or cell reselection. The candidate cells in the LTE system may be intra-frequency cells or inter-frequency cells.

Furthermore, in fig. 2, the cells (201, 202, and 203) depict a homogeneous deployment scenario (macro-network only), when the signal strength from the serving cell 201 falls below a threshold specified by s-metric (s-measure), inter-frequency measurements are triggered appropriately based on the measurement rule of s-metric because the UE100 starts inter-frequency measurements. The UE100 performs cell search with a measurement gap of 6ms every 40ms or 80ms according to the configured measurement gap pattern in the measurement configuration. In macro-only networks, there is no significant impact on the battery consumption of the UE100, since the applicability of the configured measurement gap pattern is governed by the s-metric. This means that UE battery consumption during measurement gaps is only present when needed for mobility purposes.

Figure 3 shows a deployment of inter-frequency pico cells within the coverage of a macro cell depicting a heterogeneous network deployment. As depicted in the figure, the inter-frequency pico cell is deployed within the coverage of a macro cell (300) operating on frequency f 1. The

pico cells

301, 302 and 303 operate on another frequency f2 different from the operating frequency of the macro cell. The pico frequency layer f2 may be used to offload macrocells 300, particularly in densely populated areas.

Currently, the third generation partnership project (3GPP) is studying improvements in heterogeneous network deployment, and an important issue is to identify and evaluate strategies for improved smaller cell discovery and identification. Deployment of smaller cells (picocells) may be done for a variety of reasons, such as to obtain increased network density and thus greater user capacity handling, support for henbs, deploy hotspots for offloading, enterprise deployment, and so forth. Inter-frequency measurements made by the UE100 and network density, which is the number of cells deployed in a given area, have an impact on its power consumption (energy is only used for the purpose of smaller cell detection).

Furthermore, it is also appreciated that if the currently available measurement gap pattern (one 6ms gap every 40 or 80 ms) is used for inter-frequency pico cell detection, there is a significant impact on UE power consumption even when a larger number of smaller cells are deployed. The currently defined measurement gap pattern was originally designed for mobility purposes and this measurement gap was designed and optimized to allow fast inter-frequency or inter-Radio Access Technology (RAT) cell search and measurement, which enables fast mobility when needed in a macro-only cell deployment scenario.

In a HetNet scenario (shown in the figure) where smaller cells are deployed as hotspots for the purpose of offloading users from the macro cell 300 (capacity scenario), the constant use of inter-frequency measurements with the current standardized measurement gap pattern and measurement rules will quickly drain the UE battery.

A method for minimizing battery power consumption of a User Equipment (UE) in a Radio Resource Control (RRC) connected mode during inter-frequency cell detection in a heterogeneous network is described herein.

In one embodiment, as depicted in the figure, the UE always has macro cell 300 coverage and inter-frequency measurements for pico cells need not be performed with a normal measurement gap period of 40ms or 80 ms.

To conserve battery power of the UE100 for pico cell detection, the network or macro cell 300 may configure the UE100 with long periodic measurement gaps. In an example, the long measurement gap may be 10 seconds or 60 seconds. With this long period measurement gap, the UE can save battery power. Once the pico cell is detected by the UE100, the network then configures the UE100 with a normal measurement gap of 40ms or 80 ms. However, increasing the measurement gap to 10 or 60 seconds would require defining new measurement performance requirements for the UE in the specification, which the present invention intends to solve.

The proposed invention addresses the above limitations by providing long period measurements in a background scan configuration (background scan configuration) by the network or macro cell 300. The UE100 receives a background scanning configuration including long period measurements for detecting inter-frequency pico cells in a heterogeneous network.

In an embodiment, the background scan configuration includes a background scan indicator that indicates to the UE100 that it may perform a background scan to detect an inter-frequency pico cell in an inactive time of a configured Discontinuous Reception (DRX) cycle. With the background scanning configuration, the network indicates for which configured frequency the UE is expected to perform cell search on that frequency using the background scanning method according to the measurement configuration (measurement object). The background scanning configuration further includes a period of scanning, a density of cells on frequency, and a list of frequencies for background scanning by the UE 100.

In an embodiment, the background scanning configuration is provided to the UE in a broadcast message or a Radio Resource Control (RRC) reconfiguration message.

In an embodiment, the network sends a background scan indicator in a broadcast message for the UE100 to start background scanning during inactive times of the configured DRX cycle for inter-frequency pico cell discovery. The broadcast indication serves as a trigger to request the UE100 to initiate a cell search on frequencies other than the serving cell frequency according to the measurement configuration.

The broadcast message triggers the UE100 to initiate a cell search in the network specified frequency according to the measurement configuration. Furthermore, the indication in the broadcast message to trigger the background scan may be applicable to all UEs in the cell or network.

In another embodiment, the network triggers the individual UEs to initiate background scanning by a "start scanning" indication in a dedicated message, so that the UE100 starts background scanning during the inactive time of the configured DRX cycle for inter-frequency pico cell discovery. In one embodiment, such a message may be an RRC connection reconfiguration message. In this option, the network may send a "start scan indicator," i.e., a background scan indicator, in an RRC connection reconfiguration message, along with a scan period and a list of frequencies in which the picocell may be found.

In an embodiment, the periodicity of such inter-frequency measurements may be determined by the UE100 itself.

In an embodiment, the periodicity of such inter-frequency measurements may be decided by the network and may be indicated to the UE100 in a broadcast message or a dedicated RRC message.

For example, the period of inter-frequency measurements may be once every 10 seconds or once a minute.

In an embodiment, the list of frequencies indicates frequency layers of the cell deployment based on Radio Access Technologies (RATs) belonging to third generation partnership project (3GPP) RATs and non-3 GPP prat.

In an embodiment, the indication to trigger the background inter-frequency measurement (i.e., the background scan indicator) may have several code-points (code-points) corresponding to the RATs of the pico cell.

In an embodiment, the UE100 may infer the periodicity of inter-frequency pico cell or inter-RAT measurements based on the code points in the background scan indicator.

The periodicity of the inter-frequency picocell search or inter-RAT cell search depends on the density of picocells.

In an embodiment, the network indicates a pico density (pico diversity) in a broadcast message or dedicated RRC message, and the UE100 can infer the period of scanning based on the pico density indicated by the network through the broadcast message or dedicated RRC message.

The scanning period and pico density may be indicated by the network in a broadcast message.

In an embodiment, the scanning period and pico density may be provided by the network in a system information block 4(SIB4) message.

In an embodiment, the network also indicates the frequency on which the pico cell is deployed. In an embodiment, the network indicates a different Radio Access Technology (RAT) on which the network wants the UE to start background scanning.

In an embodiment, when the network has issued a background scan configuration to the UE to trigger an inter-frequency/inter-RAT background scan (measurement), the UE performs cell search (measurement) during the inactive time of the configured DRX cycle. The UE100 may take several inter-frequency scans for detecting pico cells during the DRX cycle with the opportunity to use available inactivity time.

In an embodiment, when the inactivity time during a particular DRX cycle is quite long (e.g., hundreds of milliseconds), the UE100 may detect inter-frequency cells in a single scan rather than in several scans.

Once the UE100 has detected an inter-frequency or inter-RAT pico cell, the UE100 reports the detected pico cell (i.e., the physical cell identity of the detected pico cell) to the network through a proximity indicator (proximity indicator).

In an embodiment, the UE100 indicates to the network the cells detected on the frequency scanned using the background scanning configuration through at least one of a proximity indication message or a dedicated RRC message.

The UE100 indicates to the network a Physical Cell Identity (PCI) of a cell detected on a frequency scanned using the background scanning configuration in a proximity indication message or an RRC message. When receiving the proximity indication message from the UE100, if a normal measurement gap is not provided in the measurement configuration in advance, the network configures the UE with a normal measurement gap of 40ms or 80 ms. Otherwise, the UE100 activates the normal measurement gap that the network has configured.

When the UE is active or receives a normal measurement gap from the network, the UE100 stops background scanning for inter-frequency measurement during the inactive time of the DRX cycle.

In an embodiment, the UE100 starts a prohibit timer (prohibit timer) after issuing the proximity indication to the network. If the normal inter-frequency measurement gap is not configured while the prohibit timer is running, the UE100 continues background scanning and reports another proximity indication if the UE100 is still in the vicinity of the inter-frequency pico cell when the prohibit timer expires.

When the UE100 activates an already configured normal measurement gap or the network configures a normal measurement gap upon receiving the PCI of the detected cell, the UE stops background scanning and the UE100 performs Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) measurements of the detected cell using the normal measurement gap. Then, the UE100 reports RSRP/RSRQ measurements to the network when the measurement reporting event condition is met, and the UE100 switches to the detected pico cell using a normal handover procedure.

In an embodiment, the network determines whether the pico cell detected by the UE100 is loaded through X2 load information. Further, the network decides whether to handover the UE to the detected pico cell based on the load in the pico cell.

The UE100 is handed over to the detected pico cell (which may be

pico cell

301 or 302 or 303) by the network, as indicated by the dashed arrow in the figure. In one embodiment, once a UE has handed over to a pico cell, that pico cell may reconfigure the UE for normal measurements.

Fig. 4 shows a flow chart illustrating a procedure involved in detecting inter-frequency cells by a user equipment using a background scanning method according to embodiments disclosed herein. As depicted in flow diagram 400, initially a UE receives (401) a background scanning configuration from a network or macro cell.

In an embodiment, the background scanning configuration is provided to the UE100 in a broadcast message or a Radio Resource Control (RRC) reconfiguration message. The background scanning configuration includes a background scanning indicator that serves as a trigger for requesting the UE100 to initiate a cell search on a frequency other than the serving cell frequency according to the measurement configuration. The UE is expected to perform inter-frequency cell search during the inactive time of the configured DRX cycle.

The background scanning configuration further includes a period of scanning, a density of cells on a frequency layer, and a list of frequencies for background scanning of the UE 100. The broadcast message or RRC reconfiguration message triggers the UE100 to initiate cell search or scan in a network-specified frequency.

The UE performs (402) a background scan for inter-frequency/inter-RAT pico cell discovery during an inactive time of the DRX cycle. The UE100 detects (403) an inter-frequency or inter-RAT cell on a designated frequency according to the frequency designated by the network for performing the background scan. Once the UE100 has detected an inter-frequency or inter-RAT cell, the UE100 sends (404) an indication to the network by means of a proximity indicator or dedicated RRC message including the Physical Cell Identity (PCI) of the detected cell.

In an embodiment, the UE100 indicates to the network the cells detected on the frequency scanned using the background scanning configuration through a proximity indication message or a dedicated RRC message. The UE100 indicates the Physical Cell Identity (PCI) of the detected pico cell to the network in a proximity indication message or a dedicated RRC message.

Furthermore, if already provided in the measurement configuration, the UE activates the normal measurement gap. If the normal measurement gap is not preconfigured, the network configures (405) the normal measurement gap of 40ms or 80ms to the UE100 upon receiving the PCI of the detected pico cell. The UE continues to use the measurement gap for inter-frequency measurements after the UE hands off to the pico cell. With the normal measurement gaps, the UE performs (406) normal RSRP and RSRQ measurements of the detected cells. When the measurement report event condition is satisfied, the UE reports RSRP/RSRQ measurements of the detected cell to the network. The network hands over (407) the UE100 to the detected pico cell using a normal handover procedure. Further, the network may decide whether to handover the UE to the detected pico cell based on the load in the pico cell. The various actions in flowchart 400 may be performed in the order presented, in a different order, or concurrently. Further, in some embodiments, some actions listed in fig. 4 may be omitted.

In an embodiment, the network may provide a set of rules to the UE based on the indicated threshold or a preconfigured threshold for the UE to decide to trigger the background scan.

In an embodiment, such rules may be a combination of UE speed, location ID, and the like.

In one embodiment, if the velocity is "medium" and the location ID is a cell ID, the UE will initiate a background scan on the provided frequency. Such rules may be indicated to the UE in a broadcast message or in a dedicated message.

When the UE is performing high data rate transmission/reception, the UE may not be configured with DRX. The network may then configure the UE for relaxed measurements (relaxed measurements) by configuring new inter-frequency measurements on that frequency with dedicated signaling. When the UE is in low throughput mode (which may even be background data), the network may configure the UE for background scanning for pico detection along with DRX configuration. When DRX is not configured and then relaxed measurements are configured, the remaining steps may be the same, i.e. after detection, the UE will send a proximity indicator and in turn the network will configure the UE with gap pattern for measuring pico cells.

In another embodiment, a simple new bit in a measurement configuration message or broadcast message indicating "delayed or relaxed detection allowed" may be sent to the UE to trigger the relaxed scanning (measurement), or a new event(s) informing "delayed or relaxed detection allowed" may be sent to the UE for triggering the relaxed pico cell scanning on a specified frequency. This indication is sent to the UE as soon as the UE enters the macro cell with overlapping pico cells. The macro cell may be aware of the existence of overlapping pico cells by any operation and maintenance (OAM) entity.

In an embodiment, when the UE100 receives an indication that the detection is allowed to be relaxed, this may mean that the minimum time it will take for the UE to detect a cell on a specified frequency is relaxed. In one example, this relaxation may be left to the UE implementation to handle, or the network may specify a relaxed detection time limit. In another example, a scale factor or code point may be provided by the network to specify the delay bound. As an example of a scaling factor, the network may provide a value of 2X to the UE and associate a time value with variable X, or the network may also provide the value of X. The value of X may also be a preconfigured minimum detection time, which may be the same time as specified for normal detection.

Fig. 5 illustrates a computing environment implementing methods and systems for minimizing battery power consumption in a user equipment during inter-frequency cell detection in accordance with embodiments disclosed herein. As depicted, the computing environment 501 includes at least one processing unit 504 equipped with a control unit 502 and an Arithmetic Logic Unit (ALU)503, a memory 505, a storage unit 506, a plurality of network devices 508, and a plurality of input/output (I/O) devices 507. The processing unit 504 is responsible for processing instructions of the algorithm. The processing unit 504 receives a command from the control unit to perform its processing. In addition, any logical and arithmetic operations involved in the execution of instructions are calculated with the help of ALU 503.

The overall computing environment 501 may be comprised of multiple homogeneous and/or heterogeneous cores, multiple heterogeneous CPUs, special media, and other accelerators. The processing unit 504 is responsible for processing instructions of the algorithm. Furthermore, the plurality of processing units 504 may be located on a single chip or on multiple chips.

Algorithms, including instructions and code required for implementation, may be stored in memory 505 or storage unit 506 or both. At run-time, instructions may be fetched from the respective memory 505 and/or storage unit 506 and executed by the processing unit 504.

In either case of a hardware implementation, multiple network devices 508 or external I/O devices 507 may be connected to the computing environment through network elements and I/O device elements to support the implementation.

The embodiments disclosed herein may be implemented by at least one software program running on at least one hardware device and performing network management functions for control elements. The elements shown in fig. 1, 2, 3, and 5 include blocks that may be at least one of hardware devices, or a combination of hardware devices and software modules.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications will be comprehended and are intended to be within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Thus, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Claims

1. A base station in a communication network, comprising:

at least one processor; and

a transceiver configured to:

transmitting information for inter-frequency measurements, including a frequency, an indication indicating that the frequency is configured for relaxed measurements, and a scaling factor for scaling a time period for the inter-frequency measurements, and

receiving a measurement report including a measurement result measured based on the information from a User Equipment (UE),

wherein the time period is scaled based on the scaling factor, and

wherein the time period of the relaxed measurement is different from the time period of the normal measurement.

2. The base station of claim 1, wherein the information is transmitted via a Radio Resource Control (RRC) message.

3. The base station of claim 1, wherein the information indicates initiation of cell search for at least one frequency during an inactive time of a Discontinuous Reception (DRX) cycle.

4. The base station of claim 1, wherein the transceiver is configured to receive a Physical Cell Identity (PCI) of a cell among the at least one searched cell and to transmit information related to a measurement report event condition.

5. The base station of claim 4, wherein the measurement report is received based on a measurement report event condition.

6. A user equipment, UE, in a communication network, comprising:

at least one processor; and

a transceiver configured to:

receiving information for inter-frequency measurements from a base station, including a frequency, an indication indicating that the frequency is configured for relaxed measurements, and a scaling factor for scaling a time period for the inter-frequency measurements, and

transmitting a measurement report including a measurement result measured based on the information to a base station,

wherein the time period is scaled based on the scaling factor, and

7. The UE of claim 6, wherein the information is transmitted via a Radio Resource Control (RRC) message.

8. The UE of claim 6, wherein the information indicates initiation of cell search for at least one frequency during an inactive time of a Discontinuous Reception (DRX) cycle.

9. The UE of claim 6, wherein the transceiver is configured to transmit a Physical Cell Identity (PCI) of a detected cell among the at least one searched cell to the base station.

10. The UE of claim 6, wherein the transceiver is configured to receive information related to a measurement report event condition, an

Wherein the measurement report is transmitted based on the measurement report event condition.

11. A method of a base station in a communication network, comprising:

transmitting information for inter-frequency measurements, including a frequency, an indication indicating that the frequency is configured for relaxed measurements, and a scaling factor for scaling a time period for the inter-frequency measurements; and

wherein the time period is scaled based on the scaling factor, and

12. The method of claim 11, wherein the information is transmitted via a Radio Resource Control (RRC) message.

13. The method of claim 11, wherein the information indicates initiation of cell search for at least one frequency during an inactive time of a Discontinuous Reception (DRX) cycle.

14. The method of claim 11, further comprising:

a Physical Cell Identity (PCI) of a cell among the at least one searched cell is received, and information related to a measurement report event condition is transmitted.

15. The method of claim 14, wherein the measurement report is received based on a measurement report event condition.

16. A method of a User Equipment (UE) in a communication network, comprising:

receiving information for inter-frequency measurements from a base station, including a frequency, an indication indicating that the frequency is configured for relaxed measurements, and a scaling factor for scaling a time period for the inter-frequency measurements; and is

wherein the time period is scaled based on the scaling factor, and

17. The method of claim 16, wherein the information is transmitted via a Radio Resource Control (RRC) message.

18. The method of claim 16, wherein the information indicates initiation of cell search for at least one frequency during an inactive time of a Discontinuous Reception (DRX) cycle.

19. The method of claim 16, further comprising:

transmitting a Physical Cell Identity (PCI) of a detected cell among the at least one searched cell to the base station.

20. The method of claim 16, further comprising:

receiving information relating to a measurement report event condition, an